Cardinality Statistic for Optimizing Database Queries with Aggregation Functions

摘要

Embodiments of the invention provide techniques for generating predicted cardinality statistics for grouped aggregation functions included in database queries. In general, characteristics of a database query are determined, and are then supplied to a probability function configured to generate a predicted cardinality statistic. The generated statistic represents a prediction of the probable cardinality of the results of a grouped aggregation function in the event that the query is executed. The predicted cardinality statistic may be used by a query optimizer to determine an efficient query plan for executing the database query.